A selection of electrical ‘how to’ guides
Welcome to my electrical ‘how to’ guide section of this website. I’ve put these guides together based upon various jobs that I’ve needed to do over the past few months on my Matchless G3Ls and what I’ve been able to pick up from various owners manuals, service guides and users forums. Whilst all of these sources have been incredibly useful, quite often I found that they weren’t completely explicit in telling the novice (me!) exactly what I needed to do.
So I thought it might be useful to put together a collection of idiot-proof guides to some common tasks with lots of photos and which take you through step-by-step. No doubt these might quite often state the obvious to the experienced classic bike owner, but when it’s your first time and your learning (and desperate not to do something wrong and ruin your new pride and joy!) then for me, a step-by-step hold your hand guide would be quite useful. I hope you’ll think so too!
The various guides are listed down the right hand side of all of the pages of this website under the not-so-surprising title of ‘How to guides’. They are split up into various categories and are also listed below.
General system checks
This is my basic beginners guide to diagnosing potential faults with the Lucas electrical system of your classic motorbike, which covers:
- Checks using the headlights.
- Verifying the ammeter readings.
- Testing the battery voltage.
- Checking the wiring and connections.
Testing a Lucas dynamo
If you suspect that your Lucas dynamo is at fault, this article will guide you through a series of simple checks and tests you can perform, including:
- Disconnecting the dyanamo.
- Checking the output with a multimeter.
- Measuring the winding resistances.
- Testing the dynamo under load.
Repolarising a dynamo
Lucas dynamos can sometimes lose their residual magnetism over time or be incorrectly polarised, so this is a step-by-step guide to repolarising which includes:
- How the Lucas dynamo works.
- When to repolarise the dynamo.
- Determining the correct polarity.
- How to ‘flash’ the dynamo safely.
Converting to 12 volts
Many classic bikes are wired with 6 volt electronics, but converting to a modern 12 volt system has many advantages. This guide includes:
- Disadvantages of 6 volt electronics.
- Advantages of converting to 12 volts.
- Selecting a modern solid-state reg.
- Upgrading the battery and fuse.
Replacing the regulator
This is a step-by-step guide to replacing the old Lucas mechanical voltage regulator unit with a modern solid-state electronic device. It covers the following topics:
- Selecting a replacement reg.
- Making the new connections.
- Selecting between 6 or 12 volts.
- Installing a fuse for protection.
Replacing the ammeter
Old ammeters often become inaccurate or fail completely over time, so this guide explains how to replace the gauge with a shiny new one, including:
- Removing the old ammeter.
- Installing the new gauge.
- Checking the wiring and connections.
- Verifying the readings are as expected.
Installing a fuse
Most classic bikes never had a fuse fitted as standard, but fitting one is simple and can save you a lot of smoke and fried wiring! This article explains:
- Why a fuse is so important.
- Where to fit the fuse(s).
- The different types of fuse available.
- Selecting an appropriate fuse rating.
Installing brake lights
Brake lights were still not fitted as standard to many bikes right up until the 1950’s, but they are essential on today’s roads. This article explains:
- Legal requirements for rear lights.
- Installing a rear brake switch.
- Installing a front brake switch.
- Changing the bulb and LED options.
Improving your headlights
The headlights on classic bikes may not be as bright as those on modern vehicles, but there are some simple things you can do to help including:
- Checking the quality of the wiring.
- Installing a headlamp relay.
- The most appropriate type of bulb.
- Selecting the optimum bulb wattage.